Wilhelm Carl Friedrich Sauer was a German pipe organ builder. One of the famous organ builders of the Romantic period, Sauer and his company W. Sauer Orgelbau built over 1,100 organs during his lifetime, amongst them the organs at Bremen Cathedral, Leipzig's St. Thomas Church, and Berlin Cathedral, which is considered to be "his final great masterpiece".

Bremen Cathedral, dedicated to St. Peter, is a church situated in the market square in the center of Bremen. The cathedral belongs to the Bremian Evangelical Church, a member of the umbrella organization Protestant Church in Germany. It is the previous cathedral of the former Prince-Archbishopric of Bremen. Since 1973, it is protected by the monument protection act.